A stack semiconductor device wherein a plurality of semiconductor devices is stacked and bonded by connecting terminals which are provided on the bottoms of thin semiconductor device packages and formed of solder balls has been conventionally known as an example of stack semiconductor devices. Such a stack semiconductor device is described below with reference to U.S. Pat. No. 6,303,997 (refer to pages 5, 6 and FIG. 3). FIG. 17 is a structural drawing of such a stack semiconductor device. A Semiconductor chip 51 is bonded to an inner lead 53 by adhesive agent 52. The inner lead 53 is electrically connected to an integrated circuit (not shown) formed in the semiconductor chip 51 by being wire bonded to an input and output pad 54 of the semiconductor chip 51 by a bonding wire 54. Furthermore, the device is sealed by resin 56. A solder ball 57 is provided on the bottom surface of the inner lead 53 as a connecting terminal which connects the semiconductor package 50 to an external component. The solder ball 57 is soldered to a connecting surface 58 provided on the top surface of the inner lead 53. Thus, a plurality of semiconductor packages 50 is bonded to each other by the solder ball 57, and stacked in layers, whereby a stack semiconductor package 200 is constructed.